Use the properties of geometric series to find the sum of the series. For what values of the variable does the series converge to this sum?

$$4 - 12z+36z^{2} - 108z^{3}+\cdots$$

sum =

domain =
(Give your domain as an interval or comma separated list of intervals; for example, to enter the region $x<-1$ and $2<x\le3$, enter (-infinity,-1), (2,3].)